John the Ripper is another popular cracking tool used in the penetration testing (and hacking) community. It was initially developed for Unix systems but has grown to be available on over 10 OS distros

4. *Metasploit Framework*

Metasploit Framework is an open source framework with which security experts and teams verify vulnerabilities as well as run security assessments in order to better security awareness

5. *Netcat*

Netcat, usually abbreviated to nc, is a network utility with which you can use TCP/IP protocols to read and write data across network connections.

6. *NMap*

Network Mapper is a free and open-source utility tool used by system administrators to discover networks and audit their security

7. *Nessus*

Nessus is a remote scanning tool that you can use to check computers for security vulnerabilities. It does not actively block any vulnerabilities that your computers have but it will be able to sniff them out by quickly running 1200+ vulnerability checks and throwing alerts when any security patches need to be made

8. *Wireshark*

WireShark is an open-source packet analyzer that you can use free of charge. With it you can see the activities on a network from a microscopic level coupled with pcap file access, customizable reports, advanced triggers, alerts, etc

9. *Snort*

Snort is a free and open-source NIDS with which you can detect security vulnerabilities in your computer

10. *Kismet Wireless*

Kismet Wireless is a intrusion detection system, network detector, and password sniffer. It works predominantly with Wi-Fi (IEEE 802.11) networks and can have its functionality extended using plugins